The present invention relates anti-HIV therapies and prophylaxis. Specifically, the invention relates to broadly neutralizing antibodies against HIV-1, nucleic acids encoding these antibodies, vectors comprising the nucleic acids and cells and pharmaceutical compositions Comprising said vectors and/or antibodies. The present invention also relates to use of the antibodies and/or vectors for the treatment and/or prevention of HIV-1 infection in a subject. Furthermore, the invention also relates to a kit containing the antibodies of the invention.
Antibodies that effectively neutralize HIV-1 represent potential templates to guide HIV-1 vaccination strategies if the molecular events that led to their elicitation could be understood and reproduced (Haynes et al. 2012; Kong et al. 2012; Moir et al. 2011; McCoy et al. 2013; Overbaugh & Morris 2012; Burton et al. 2012). Virtually all infected individuals mount a potent antibody response within a few months of infection, but these antibodies preferentially neutralise the autologous virus that rapidly escapes (Montefiori et al. 1991; Richman et al. 2003; Wei et al. 2003; Bunnik et al. 2008). Cross-reactive antibodies capable of neutralising a majority of HIV-1 strains arise in about 20% of donors after 2-3 years of infection (van Gils et al. 2009; Gray et al. 2011; Piantadosi et al. 2009; Sather et al. 2009; Doria-Rose et al. 2010). The challenge with studying (and eliciting) broadly neutralising antibodies is that they are generally subdominant responses and are vastly outnumbered by ineffective or strain-specific antibody responses (Kong et al. 2012; Overbaugh & Morris 2012; Pantophlet et al. 2006; Kwong et al. 2012; Mascola & Haynes et al. 2013). Importantly, it is unclear if broadly neutralizing antibodies develop from early strain-specific B cell lineages that mature over years of infection, or if breadth results from rare stochastic events stimulating new B cell lineages that rapidly become cross-reactive for HIV-1.
One means to map molecular events leading to the development of an HIV-1-specific antibody response involves the isolation of broadly neutralizing monoclonal antibodies and examination of the B cell genetic record with next-generation sequencing (NGS) (Glanville et al. 2009; Tian et al. 2008; Briney et al. 2012; Boyd et al. 2010). Sampling at a single time point after the development of a neutralizing antibody lineage allows the study of an expanded antibody family and the elucidation of earlier lineage sequences with lower levels of somatic mutation (Wu et al. 2011; Zhu et al. 2012; Zhu et al. 2013). Even greater insight can be gained with longitudinal sampling from early after the time of infection, as was shown for the CH103 antibody lineage that targets the CD4-binding site of the HIV-1 envelope glycoprotein (Env) (Liao et al. 2013). Several mature CH103 neutralizing monoclonal antibodies were isolated 2 antigen-specific B cells at 136 weeks after infection. NGS was then used to identify transcripts of the CH103 lineage, which were observed as early as 14 weeks after infection, well before plasma cross-neutralizing activity was detected in this donor. Notably, the inferred unmutated common ancestor (UCA) of CH103 bound the autologous transmitted/founder virus, and evolved in response to viral diversification to gain the necessary somatic mutations to effectively neutralize heterologous strains of HIV-1. Since the CD4 binding site is only one of the several conserved neutralization epitopes on the HIV-1 Env, additional studies are needed to understand the genetic determinants and maturation pathway of potent neutralizing antibodies that target other vulnerable regions of HIV-1.
Serum neutralizing antibodies from HIV-1 infected donors often target the V1V2 region of HIV-1 Env (Gray et al. 2011; Walker et al. 2010; Lynch et al. 2011; Tomaras et al. 2011), and binding antibodies to this region were shown to correlate with protection in the RV144 HIV vaccine trial (Haynes et al. 2012). In addition, potent neutralizing monoclonal antibodies to the V1V2 region have been isolated from several donors. These include PG9 and PG16, which neutralize 70-80% of circulating HIV-1 isolates (Walker et al. 2009), CH01-04, which neutralize 40-50% (Bonsignori et al. 2011), and PGT141-145 which neutralize 40-80% (Walker et al. 2011). All of these antibodies are characterized by long 3d-heavy-chain complementarity-determining regions (CDR H3), which are protruding, anionic, and tyrosine sulphated (Pejchal et al. 2010; McLellan et al. 2011; Pancera et al. 2013). Crystal and electron microscopy structures of Env complexes with PG9 and PG16 reveal that the CDR H3s penetrate the HIV-1 glycan shield, recognizing a quaternary glycopeptide epitope at the membrane-distal apex of the HIV-1 spike, formed by the association of V1V2s from three gp120 protomers (McLellan et al. 2011; Pancera et al. 2013; Julien et al. 2013). To understand more precisely which factors are crucial in the pathway toward effective V1V2-directed antibodies, we analyzed donor CAP256 who was previously shown to develop a potent V1V2-directed plasma response (Moore et al. 2011; Moore et al. 2013; Georgiev et al. 2013). This donor was analyzed by longitudinal sampling, found to be superinfected at week 15, and showed modest neutralization breadth at one year. By three years post-infection, plasma from CAP256 neutralized 77% of all HIV-1 strains but particularly those from subtypes A and C (Gray et al. 2011). Here we isolate potent V1V2-directed broadly neutralizing antibodies from this donor, perform NGS to enable a detailed understanding of the evolution of lineage, and determine crystal structures to define their molecular characteristics. Circulating plasma virus was also analyzed longitudinally to understand the interplay between viral Env evolution and the immune response. The results allow for a precise delineation of the molecular events that gave rise to this category of potent antibodies.